When people hear the word "agriculture," most think of food. But the benefits of agriculture are much more than farm fresh corn or dairy products. Now scientists are investigating how farmers can manage their land to offer everyone more environmental benefits, and whether farmers could be paid for providing these benefits.

"Agriculture, which includes planted forests, is the world's largest human-managed ecosystem," said Scott Swinton, professor of agricultural economics at Michigan State University. "There is a huge area of land that people manage for food, fiber and fuel – these are all marketed products with a value attached to them. What we want to know is if we can also manage agriculture for things that people like and appreciate, but don't have markets, such as cleaner air, cleaner water, less global warming, wildlife habitat and aesthetics – many people enjoy seeing the green, open space of farmland in their communities."

Swinton speaks at a symposium entitled "Harvesting Ecosystem Services from Agriculture" today at the American Association for the Advancement of Science annual meeting. The symposium will be moderated by Frank Lupi, associate professor of agricultural economics and fisheries and wildlife at MSU. They and the other participants will discuss the concept of ecosystem services – the services provided to humans by the biological processes in the ecosystem, in this case, agriculture.

Swinton, who studies sustainable agriculture, thinks the idea of ecosystems services is timely. As international trade becomes increasingly more open, many of the protections given to agricultural products are being reduced. By looking at the entire gamut of products (both marketed and unmarketed) that agriculture provides, decision-makers can make more informed choices about whether, how and why farming can be supported. The principles behind the ecosystem services idea could allow farmers to be supported if they successfully improve the environment and strengthen nature's benefits to society.

"It's pretty exciting to be involved in this," Swinton said. "For many years, the focus of sustainable agriculture has been on avoiding negatives: water pollution, soil erosion, pesticide residues, etc. In the ecosystems services concept, we're focusing on services that people appreciate and enjoy. Since the amount of land involved in agriculture is so large, we have a strong motivation to provide farmers incentives to support the ecosystem."

The Millennium Ecosystem Assessment, launched by the United Nations in 2001, defines four broad categories of ecosystem services.

Provisioning services are the products from ecosystems, including genetic resources, food and fiber, and fresh water.

Regulating services are the benefits people get from the regulation of ecosystem processes, including water supplies, temperature moderation (think how trees around a house keep it cooler in the summer) and some human disease regulation (having enough nutritious food keeps people healthy and reduces diseases such as rickets and scurvy).

Cultural services are the non-material benefits people receive from ecosystems through spiritual enrichment, cognitive development, reflection, recreation and aesthetic experiences. Put simply, hiking trails, camping areas, a lake to swim or fish in, are all benefits from nature.

Supporting services are ecosystem services that are necessary for all other ecosystem services. Some examples: production of plant materials and microbes that enrich the soil and allows crops and other plants to grow; oxygen production, which makes it possible for humans and animals to breathe; and water cycling, which nourishes plants and animals and refills lakes, streams and reservoirs.

"We know that low-input, sustainable agriculture produces improved water and soil quality, contributes to climate stability and boosts beneficial insect populations, compared to conventional crop production practices," Swinton said. "Now we want to figure out which policies would encourage farmers to provide these ecosystem services, as well as how much citizens are willing to pay for the services."